Pressure Dependent Structural, Electronic and Optical Properties of Cs2AgBiI6: A First-Principles Study

The non-toxic, lead-free halide double perovskite Cs
2
AgBiI
6
is a promising semiconductor material for optoelectronic applications. In this article, we demonstrate that material properties can be enhanced under applied pressure. Using density functional theory (DFT), we analyze structural, electronic, and optical traits of Cs
2
AgBiI
6
under different hydrostatic pressures. Increasing pressure leads to an inversely nonlinear reduction in lattice parameters. It also causes the indirect energy band gap to nonlinearly decrease, ultimately leading to a semiconductor-to-metal transition near 18 GPa. Moreover, the refractive index, absorption coefficient and reflectivity of the material also improved. With increased pressure, a redshift in the absorption spectra is observed for the absorption peaks in both the visible and ultraviolet ranges. Additionally, there has been a noticeable improvement in UV absorption, indicating their potential for future optoelectronic devices.